You must plan the capacity and time required for a cluster size of the vRealize Operations Manager system.

Calculate Bandwidth for vSphere Replication

To determine the bandwidth that vSphere Replication requires to replicate virtual machines efficiently, you should calculate the maximum data change rate within an RPO period divided by the link speed.

If you have groups of virtual machines that have different RPO periods, consider that the replication of all machines in all groups will trigger at the same time while calculating the bandwidth. This way the biggest amount of data will be considered.

For example, you might have four groups with RPO of 15 minutes, 1 hour, 4 hours, and 24 hours. Factor in all the different RPOs in the environment, the subset of virtual machines in your environment that is replicated, the change rate of the data within that subset, the amount of data changes within each configured RPO, and the link speeds in your network.

Examine how data change rate, traffic rates, and the link speed meet the RPO, and then look at the aggregate of each group.

  1. Identify the average data change rate within the RPO by calculating the average change rate over a longer period, and then dividing it by the RPO.

  2. Calculate how much traffic this data change rate generates in each RPO period.

  3. Measure the traffic against your link speed.

    For example, a data change rate of 100 GB requires approximately 200 hours to replicate on a T1 network, 30 hours to replicate on a 10 Mbps network, 3 hours on a 100Mbps network.

For information about calculating bandwidth requirements for vSphere Replication, see the Knowledge Base article at http://kb.vmware.com/kb/2037268.

For estimating average RPO, network bandwidth requirements, or the number of virtual machines that can be replicated, use the vSphere Replication calculator available on http://www.vmware.com/vrcalculator.

Sample Test Measurements

The following table displays the results of the internal measurements for a controlled lab environment, where vRealize Operations Manager instance was replicated to a recovery site. This information can be used as a guideline while calculating necessary replication bandwidth. Results may vary in your environment.

20,000 VMs, 8 nodes, HA is disabled

RPO time configured on the replication settings

1 hour

4 hours

6 hours

8 hours

Max amount of data accumulated for replication on the vRealize Operations Manager cluster during that period (all nodes)

< 16GB

< 60GB

< 130GB

> 130GB

Bandwidth required to satisfy RPO time

~ 23 MB/sec

~ 26 MB/sec

~ 31 MB/sec

> 31 MB/sec

Interval of time for each replication was measured by measuring the start and the stop time.

The test lab consisted of the following infrastructure and characteristics :

  • 2 vCenter instances with vSphere Replication and Site Recovery Manager 6.0.

  • Replication interval was initially set to 4h, later changed to 6h and finally to 8h. Independent measurements were performed for each time interval.

  • vRealize Operations Manager cluster configuration consisted of 8 nodes:

    • vROps-1. Master node

    • vROps-2. Replica node

    • vROps-3. Data node 1

    • vROps-4. Data node 2

    • vROps-5. Data node 3

    • vROps-6. Data node 4

    • vROps-7. Remote Collector node 1

    • vROps-8. Remote Collector node 2

  • vRealize Operations Manager was monitoring 20,000 virtual machines at the vCenter

  • End Point Operations (EPOps) Management Agents were not configured

  • High Availability was disabled while testing.